A modest bump in popularity for US presidential hopeful Mitt Romney from this week's Republican Party convention looks to be short-lived, according to a Reuters/Ipsos poll.
Democratic President Barack Obama regained a narrow lead on Saturday by 44% to 43% over his Republican challenger,
former Massachusetts Governor Romney, in the latest daily installment of the four-day rolling poll.

Romney was ahead by one point in Friday's online poll and two points in Thursday's survey as his campaign came under a blaze of media attention at the convention in Tampa, Florida.

In his acceptance speech on Thursday, Romney urged voters to get behind him and help rebuild the economy. His address followed three days of speeches by Republicans, including testimonies from Romney's relatives and friends aimed at improving the image of a candidate who is often seen as stiff or aloof.

"This wasn't a lightning bolt convention," Ipsos pollster Julia Clark said. "Comparatively speaking, this was a more muted convention in general ... So it doesn't surprise me that (the bump in polls) wasn't a great deal bigger."

Post-convention poll bounces are common and typically short-lived, and Obama could see one himself next week after he formally accepts his party's nomination for a second term at the Democratic convention in Charlotte, North Carolina.

But with the candidates treading water in a dead-heat race, Clark said she expected polls to remain extremely close all the way to the November 6 vote.

Romney's muted benefit from the convention may be in part because of his decision to unveil his vice-presidential pick, Wisconsin congressman Paul Ryan, weeks before the convention.

The convention was also overshadowed by Hurricane Isaac, which caused the cancellation of Monday's events, as well as a bizarre performance right before Romney's speech of Hollywood star Clint Eastwood, who addressed an imaginary Obama in an empty chair.

The Reuters/Ipsos rolling poll measures sentiment during the two-week convention season by polling over the previous four days.

The survey released on Saturday found that of registered voters who have seen, heard or read at least something about the convention, 39% thought it was excellent or good, with nearly as many saying it was average.

Among Republicans, 65% said the convention went well and 31 percent rated it average.

On Friday, the poll found Romney improving his standing with voters on various favorable characteristics, such as being "a good person" or "tough enough for the job."

Those gains largely ebbed on Saturday, but Romney continued to rise in the key category of likeability. 32% of those surveyed found him likeable, a one-point gain from Friday. Obama's likeability lost one point to 47%.

The two candidates also emerged neck-in-neck in the question of who "has the right values," with Romney at 38% and Obama at 39%. On Monday, Obama led in this category by nine points with 43%.

For the survey, a sample of 1,505 of American registered voters was interviewed online. The precision of the Reuters/Ipsos online polls is measured using a credibility interval. In this case, the poll has a credibility interval of plus or minus 2.9 percentage points.